1. Technical Field
The present disclosure relates to multi-turns angle controlling field, more particularly to a multi-turn angle controlling method based on an absolute position encoder and a device.
2. Description of Related Art
Absolute position encoders have been widely adopted in angle measurement, length measurement, and positioning control. The absolute position encoders determine each unique position via the mechanical position, and may obtain the location information instantly without memorizing and locating reference points. Considering 12-bit sampling-accuracy as an example, the 12-bit absolute position encoder is divided by 4096 engraved lines around the code plate, i.e. the 12-bit absolute position encoders represent the circumference angle in a range from 0 to 4095. In the single-turn absolute position encoders, i.e. the concept is within one circle, the corresponding angle within 360 degrees is represented in the range from 0 to 4095. In the multi-turn absolute position encoders, i.e. the concept is within multiple circles, same sample value may represent different meanings. Such as, sample value 1024 (4095/4) may represent the position of 90 degrees, 360+90 degrees, and 720+90 degrees. Therefore, a problem may occur in adopting the sample value which is the sample value may not accurately represent the position to be controlled in the multi-turn absolute position encoders, such as 1024 may not represent 360+90 uniquely. Due to the absolute position encoders are cyclical cycle in the range from 0 to 4095, the sample value may not be a control reference directly with respect to the positioning control. Such as a sample value moves from a position 4000 to a position 100, and a difference between the starting position and the target position is −3900 (100−4000), while another sample value moves from the position 4000 to a position 4095, the difference between the starting position and the target position is 95 (4095−4000). In fact, the distance from the position 4000 to the position 100 is further than that from the position 4000 to the position 4095. The difference between the positions may not correspond to the actual operation distance. Therefore, the cyclical values bring inconvenience and complexity on logical processing with respect to the actual control.